Association of glycated hemoglobin at an early stage of pregnancy with the risk of gestational diabetes mellitus among non‐diabetic women in Japan: The Japan Environment and Children’s Study

Aims/IntroductionGestational diabetes mellitus (GDM) is one of the most common complications of pregnancy and is associated with adverse pregnancy outcomes. This study aimed to explore the associations between glycated hemoglobin (HbA1c) levels at the early stage of pregnancy and the GDM risk among non‐diabetic women in a nationwide study in Japan. In addition, the relationship between GDM and adverse pregnancy outcomes was also analyzed.Materials and MethodsThis cohort study (n = 89,799) used data from the Japan Environment and Children’s Study. We stratified the participants into four groups according to HbA1c levels at an early stage of pregnancy. We investigated the association of HbA1c at an early stage of pregnancy with the risk of GDM, and of GDM with the risk of some representative adverse pregnancy outcomes, using the multiple logistic regression model with adjustment for potential confounders.ResultsThe adjusted odds ratio for GDM per 0.1 percentage point increase in HbA1c (%) was 1.20. The adjusted odds ratio for developing GDM was significantly increased in women from the HbA1c 5.0–5.4% category. GDM significantly increased the adjusted odds ratio for adverse pregnancy outcomes, such as hypertensive disorders of pregnancy, polyhydramnios and premature birth.ConclusionsHigh‐normal HbA1c levels at the early stage of pregnancy are significantly associated with GDM risk in women in Japan. GDM was significantly associated with adverse pregnancy outcomes.     

Emergency stent placement after descending aortic replacement with chronic aortic dissection

A 49-year-old man with asymptomatic chronic aneurysmal dissection was admitted to our hospital. He had undergone ascending aortic replacement for type A aortic dissection 7 months before. We performed descending aortic replacement for chronic aneurysmal dissection. Renal dysfunction appeared 1 day after the operation. Contrast-enhanced computed tomography indicated that the true lumen was severely compressed by a false lumen, and that the origins of the renal artery were occluded. We performed emergency endovascular stent placement to dilate the true lumen. Immediately after this procedure, renal ischemia improved. The postoperative course was uneventful. An endovascular approach using bare stent can be a treatment option that is less invasive and prompter for a patient with renal ischemia resulting from aortic dissection.     

Probing the binding specificities of human Siglecs by cell-based glycan arrays

Siglecs are a family of sialic acid–binding receptors expressed by cells of the immune system and a few other cell types capable of modulating immune cell functions upon recognition of sialoglycan ligands. While human Siglecs primarily bind to sialic acid residues on diverse types of glycoproteins and glycolipids that constitute the sialome, their fine binding specificities for elaborated complex glycan structures and the contribution of the glycoconjugate and protein context for recognition of sialoglycans at the cell surface are not fully elucidated. Here, we generated a library of isogenic human HEK293 cells with combinatorial loss/gain of individual sialyltransferase genes and the introduction of sulfotransferases for display of the human sialome and to dissect Siglec interactions in the natural context of glycoconjugates at the cell surface. We found that Siglec-4/7/15 all have distinct binding preferences for sialylated GalNAc-type O-glycans but exhibit selectivity for patterns of O-glycans as presented on distinct protein sequences. We discovered that the sulfotransferase CHST1 drives sialoglycan binding of Siglec-3/8/7/15 and that sulfation can impact the preferences for binding to O-glycan patterns. In particular, the branched Neu5Acα2–3(6-O-sulfo)Galβ1–4GlcNAc (6′-Su-SLacNAc) epitope was discovered as the binding epitope for Siglec-3 (CD33) implicated in late-onset Alzheimer’s disease. The cell-based display of the human sialome provides a versatile discovery platform that enables dissection of the genetic and biosynthetic basis for the Siglec glycan interactome and other sialic acid–binding proteins.

Immune cells are equipped with an array of glycan-binding proteins (GPBs) capable of interpreting the biological information encoded by glycans. Endogenous GBPs recognize host-derived “self” and foreign-derived “nonself” glycans and produce cues that are integrated into the signaling network of immune cells and contribute to immune homeostasis and the immune response (1). Siglecs (sialic acid–binding immunoglobulin-like lectins) serve in self-recognition and transmit immune inhibitory signals upon binding to a select repertoire of sialoglycans expressed by host cells raising the threshold for immune activation (2, 3). The human Siglec family consists of 14 functionally expressed members, and these are composed of an N-terminal V-set immunoglobulin (Ig)-like domain that mediates sialoglycan binding followed by varying numbers of C2-set Ig-like domains. Intracellularly, most Siglecs have immunoreceptor tyrosine-based inhibition motifs, and Siglec-14/15/16 carry immunoreceptor tyrosine-based activation motifs (3–7). Siglecs are broadly expressed throughout the immune system, and several Siglecs are also found outside of the immune system, such as Siglec-4 (MAG), which is expressed by oligodendrocytes and Schwann cells in the nervous system (8). Although the diverse biological functions within and outside of the immune system of Siglecs are not fully understood, Siglecs generally contribute to immune homeostasis by dampening immune activation upon recognition of sialoglycans. For example, Siglec-2 (CD22) can suppress B cell receptor activation (9), and Siglec-9 can dampen neutrophil activation (10). Cancer cells with aberrant sialoglycans and pathogens that express sialic acids can exploit Siglec signaling to modulate immune responses (11, 12). Moreover, Siglec-3 (CD33) is strongly associated with risk for Alzheimer’s disease and expressed on microglia cells (13, 14). Given the potent immune modulatory functions of Siglecs and their wide involvement in autoimmunity, infection, cancer, and neurodegeneration, Siglecs are promising therapeutic targets (7, 15). However, many of the natural ligands of Siglecs have not been fully identified, and endogenous ligands for several Siglecs including Siglec-3/CD33 remain elusive.Human cells can produce a large diversity of glycans capped with sialic acids (Sia), a family of chemically diverse sugars with N-acetylneuraminic acid (Neu5Ac) being the predominant type in humans. Sialic acids are generally found at the termini of mammalian glycans, and most types of glycoconjugates including N-glycoproteins, multiple types of O-glycoproteins, and glycolipids carry oligosaccharides capped by sialic acids (16, 17). Sialylation is one of the most complex regulated steps in glycosylation with 20 distinct Golgi-located sialyltransferase isoenzymes dedicated to catalyze transfer of sialic acids to galactose (ST3GAL1-6, ST6GAL1 and 2), N-Acetylgalactosamine (Gal-NAc) (ST6GALNAC1-6), or sialic acid (ST8SIA1-6) via α2-3, α2-6, or α2-8 linkages, respectively and with different preferences for the underlying glycan structures and types of glycoconjugate (18–20). The resulting plethora of sialic acid-containing glycans constituting the sialome of cells provides a vast catalog of ligands for Siglecs and potential for distinct instructive cues for the immune response (16). The current insight into the interactome of Siglecs is largely derived from studies with libraries of synthetic and natural glycans printed on glass arrays (21, 22). These glycan arrays have demonstrated distinct structural glycan features that drive selective binding of individual Siglecs, including the linkage type of sialic acids, the core disaccharide carrying sialic acids, and glycan modifications such as sulfation or acetylation (23–27). However, printed glycan arrays may not present glycans in the natural context of the overall glycoconjugate structure and the cell surface with spatial organization and competition dynamics limiting insight into the fine binding specificities of Siglecs and their interactions with the host cell sialome.Here, we took advantage of our recently developed cell-based glycan array strategy (28–30) and generated an expanded sialome sublibrary with the human embryonic kidney (HEK) 293 for dissection of Siglec binding properties. First, combinatorial gene knockout (KO) was used to delete distinct subsets of sialyltransferase isoenzymes or all endogenous sialylation capacity. Second, using targeted gene knock-in (KI), individual sialyltransferase isoenzymes were introduced in the absence of other isoenzymes. Finally, we introduced selected sulfotransferase isoenzymes to explore cross-talk between sialylation and sulfation. To specifically address the influence of clustered O-glycan presentation for Siglec binding, we introduced a large panel of reporter constructs designed to display human O-glycodomains derived from mucins and mucin-like O-glycoproteins with different densities and patterns of O-glycans. The cell-based sialome array reproduced previous results for binding specificities for Siglec-2 (CD22) and Siglec-9 and led to insight into the binding specificities of Siglec-4/7/15 for distinct GalNAc-type O-glycans and their presentation on O-mucin–like glycoproteins. Finally, we demonstrate that Siglec-3/7/8/15 have preferential binding to sulfated sialoglycans yet have different specificities for underlying glycoconjugate structures. We further discovered the 6′-Su-SLacNAc (Neu5Acα2-3[6-O-sulfo]Galβ1-4GlcNAc) epitope on N-glycans and glycolipids as the ligand for Siglec-3/CD33 as well as Siglec-8. In summary, the cell-based display of the human sialome enables dissection of the Siglec interactome in the natural context of a human cell and provides the biosynthetic and genetic basis for the identified ligands.     

Sympathoexcitation by brain oxidative stress mediates arterial pressure elevation in salt-induced chronic kidney disease

Hypertension is very prevalent in chronic kidney disease and critical for its prognosis. Sympathoexcitation and oxidative stress have been demonstrated to be involved in chronic kidney disease. We have shown previously that sympathoexcitation by brain oxidative stress mediates arterial pressure elevation in the salt-sensitive hypertension model, Dahl salt-sensitive rats. Thus, we investigated whether sympathoexcitation by excessive brain oxidative stress could contribute to arterial pressure elevation in salt-induced chronic kidney disease model rats. Young (3-week-old) male Sprague-Dawley rats were randomly assigned to a uninephrectomy or sham operation and then subjected to either a normal salt (0.5%) or high-salt (8.0%) diet for 4 weeks. The young salt-loaded uninephrectomized rats exhibited sympathoexcitation, hypertension, and renal injury, proteinuria and global glomerulosclerosis together with tubulointerstitial damage. Under urethane anesthesia and artificial ventilation, renal sympathetic nerve activity, arterial pressure, and heart rate decreased to a greater degree in the salt-loaded uninephrectomized rats than in the nonsalt-loaded uninephrectomized rats and the salt-loaded or nonsalt-loaded sham-operated rats, when Tempol, a membrane-permeable superoxide dismutase mimetic, was infused acutely into the lateral cerebral ventricle. Oxidative stress in the hypothalamus, measured by lucigenin chemiluminescence, was also significantly greater. Furthermore, in the salt-loaded uninephrectomized rats, antioxidant treatment with chronic intracerebroventricular Tempol decreased sympathetic nerve activity and arterial pressure, which, in turn, led to a decrease in renal damage. Similar effects were elicited by treatment with oral moxonidine, the central sympatholytic agent. In conclusion, sympathoexcitation by brain oxidative stress may mediate arterial pressure elevation in salt-induced chronic kidney disease.     

Protective Role of Nitric Oxide in Staphylococcus aureus Infection in Mice

This study was carried out to determine the role of nitric oxide (NO) in Staphylococcus aureus infection in mice. NO production in spleen cell cultures was induced by heat-killed S. aureus. Expression of mRNA of the inducible isoform of NO synthase (iNOS) was induced in the spleens and kidneys of S. aureus-infected mice. When mice were treated with monoclonal antibodies (MAbs) against tumor necrosis factor alpha (TNF-α) or gamma interferon (IFN-γ) before S. aureus infection, the induction of iNOS mRNA expression in the kidneys was inhibited. These MAbs also inhibited NO production in spleen cell cultures stimulated with heat-killed S. aureus. NO production in the spleen cell cultures and levels of urinary nitrate plus nitrite were suppressed by treatment with aminoguanidine (AG), a selective inhibitor of iNOS. The survival rates of AG-treated mice were significantly decreased by either lethal or sublethal S. aureus infections. However, an effect of AG administration on bacterial growth was not observed in the spleens and kidneys of mice during either type of infection. Production of TNF-α and IFN-γ was not affected by AG treatment in vitro and in vivo. These results suggest that NO plays an important role in protection from lethality by the infection, but the protective role of NO in host resistance against S. aureus infection was not proved. Moreover, our results show that TNF-α and IFN-γ regulate NO production while NO may not be involved in the regulation of the production of these cytokines during S. aureus infection.     

Identification of sna41 gene, which is the suppressor of nda4 mutation and is involved in DNA replication in Schizosaccharomyces pombe

Background

The replication licensing factor limits DNA replication to once in a cell cycle and is thought to contain MCM proteins as its component parts. Six MCM subtypes have been identified in various species. These MCM proteins are thought to bind each other to make a heteromeric complex. The Nda4 protein of Schizosaccharomyces pombe is one of the MCM proteins and is involved in DNA replication.

Results

The suppressor mutant of nda4 was isolated and the mutant gene was named sna41. The sna41-912 mutant demonstrated the ts phenotype, with an elongated cell shape at the restrictive temperature. Cells with 1C DNA content accumulated 2 h after shifting up to the restrictive temperature. This result suggests that sna41 is also involved in DNA replication. The sna41 genomic clone was isolated by a complementation of the ts phenotype of the mutant strain and was sequenced. The sna41 gene encodes a protein of 638 amino acids, which has low homology with CDC45 in S. cerevisiae. The gene disruption analysis showed that sna41 gene is essential for viability.

Conclusions

The S. pombe sna41 mutation suppresses the nda4-108 mutation. Sna41 is involved in DNA replication and may play some roles in the regulation of DNA replication by the MCM proteins.

     

Esophageal function worsens with long duration of diabetes

BACKGROUND: The aim of this study was to assess the relationship between the duration of diabetes and esophageal dysfunction. METHODS: We examined 66 patients with type 2 diabetes. Duration of diabetes was determined by asking patients and from their medical records. The patients were divided into three groups according to the duration of their diabetes: group A, 1-4 years, n=26; group B, 5-9 years, n=20; and group C, 10+ years, n=20. Ambulatory esophageal 24-h pH and motility were monitored, and gastroesophageal reflux and esophageal motility disorders were estimated in detail. RESULTS: When the duration of diabetes was long, the percentage of time with pH<4 tended to increase. The amplitude of esophageal peristaltic waves and the frequency of effective peristalsis were reduced when the duration of diabetes was long. A significant correlation was observed between the duration of diabetes and the frequency of effective peristalsis. The number of esophageal peristaltic waves per minute and the percentage of multipeaked peristaltic waves increased significantly in group B, and decreased when the duration of diabetes became longer. CONCLUSIONS: Gastroesophageal reflux and esophageal motility disorders worsened with long duration of diabetes. These esophageal dysfunctions should be considered in patients with long-standing diabetes.